/*
c * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.api.common.io;

import org.apache.flink.annotation.Public;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.api.common.functions.RuntimeContext;
import org.apache.flink.core.io.InputSplit;

import java.io.IOException;

/**
 * An abstract stub implementation for Rich input formats.
 * Rich formats have access to their runtime execution context via {@link #getRuntimeContext()}.
 */
@Public
public abstract class RichInputFormat<OT, T extends InputSplit> implements InputFormat<OT, T> {
	
	private static final long serialVersionUID = 1L;
	
	// --------------------------------------------------------------------------------------------
	//  Runtime context access
	// --------------------------------------------------------------------------------------------
	
	private transient RuntimeContext runtimeContext;

	public void setRuntimeContext(RuntimeContext t) {
		this.runtimeContext = t;
	}
	
	public RuntimeContext getRuntimeContext() {
		if (this.runtimeContext != null) {
			return this.runtimeContext;
		} else {
			throw new IllegalStateException("The runtime context has not been initialized yet. Try accessing " +
			"it in one of the other life cycle methods.");
		}
	}

	/**
	 * Opens this InputFormat instance. This method is called once per parallel instance.
	 * Resources should be allocated in this method. (e.g. database connections, cache, etc.)
	 * 
	 * @see InputFormat
	 * @throws IOException in case allocating the resources failed.
	 */
	@PublicEvolving
	public void openInputFormat() throws IOException {
		//do nothing here, just for subclasses
	}

	/**
	 * Closes this InputFormat instance. This method is called once per parallel instance.
	 * Resources allocated during {@link #openInputFormat()} should be closed in this method.
	 * 
	 * @see InputFormat
	 * @throws IOException in case closing the resources failed
	 */
	@PublicEvolving
	public void closeInputFormat() throws IOException {
		//do nothing here, just for subclasses
	}
}
